1. Field of the Invention
The present invention relates to an electronic computing apparatus such as an electronic portable calculators and an electronic pocketbook, capable of carrying out an arithmetic operation in accordance with a functional expression or equation, and to an arithmetic processing method.
2. Description of Related Art
Hitherto, there have been known electronic computing apparatuses capable of processing an arithmetic operation in accordance with a functional expression or an equation. Such computing apparatus comprises an input section and executes the arithmetic processing in accordance with a functional expression or equation when such expressions are inputted and it is specified to execute the arithmetic processing. The result of the arithmetic processing is displayed as a graph or the like on a display for example provided in the computing apparatus.
The above-mentioned functional expression or equation is inputted by using a plurality of numeric keys, symbol keys and arithmetic symbol keys provided at the input section. For instance, they are inputted by using trigonometric function keys of sin, cos and tan, inverse trigonometric function keys of sin.sup.-1, cos.sup.-1, tan.sup.-1, a x.sup.2 (square) key, a x.sup.-1 (inverse number) key, logarithmic function keys of log and ln, exponential function keys of 10.sup.x and e.sup.x, a .pi. (ratio of the circumference of a circle to its diameter) key, an a/b (fraction) key, an a.sup.b (power) key, a (square root) key, a .sup.a (radical root) key, an abs (absolute value) key, a n! (factorial) key, a nCr (combination) key, a nPr (permutation) key, hyperbolic function keys of sin h, cos h and tan h, inverse hyperbolic function keys of sin h.sup.-1, cos h.sup.-1, tan h.sup.-1, an .intg. (integral function) key, numeric keys of 0 through 9, keys of four fundamental rules of +, -, .times., .div. and (,) and alphabet keys. A technology for inputting an arithmetic expression by using such plurality of keys has been disclosed in Japanese Unexamined Patent Publication JP-A 61-269764 for example.
However, it has been troublesome and annoying for users to complete and to input such a functional expression or an equation by selecting desired keys among such many keys as described above to cause the electronic computing apparatus to execute the arithmetic processing in accordance with the functional expression or the equation.